Liquid crystal display devices are widely used as image display devices for displaying color images. Many conventional liquid crystal display devices display color images using color filters. Further, field sequential type liquid crystal display devices are known as a liquid crystal display device for displaying color images without using color filters.
Typically, a field sequential type liquid crystal display device is provided with a backlight including light sources of red, green, and blue, and displays three fields of red, green, and blue in one frame period. When the red field is to be displayed, a liquid crystal panel is driven based on red video data, and the red light source emits light. Then, the green field and the blue field are displayed in a similar manner. The three fields displayed by time division are combined based on an afterimage effect on an observer's retina, and thus would be recognized as a single color image by the observer.
In the field sequential type liquid crystal display device, the observer often sees colors of these three fields separated when a line of sight of the observer moves within a display screen. This phenomenon is called as a color breakup. Displaying a white field in addition to red, green, and blue fields is conventionally known as a method of reducing color breakup. Aside from this, controlling brightness of the backlight for each area according to video data is known as a method of reducing power consumption of liquid crystal display devices.
Patent Document 1 describes an image display device that controls brightness of a backlight for each area, and displays white, red, green, and blue fields (see FIG. 15). The image display device shown in FIG. 15 performs resolution reduction processing to input video signals Rorg, Gorg, and Borg to obtain light emission patterns BLr, BLg, and BLb of the backlight for each partial light emitting area. Then, the image display device generates partial driving video signals R, G, and B by dividing the input video signals Rorg, Gorg, and Borg by results obtained when diffusion processing is applied to the light emission patterns BLr, BLg, and BLb, and extracts a common white component Wcom from the partial driving video signals R, G, and B. Patent Document 2 describes a field sequential video display device that resolves one frame of a video signal into a plurality of fields, the number of the fields being greater than the number of colors of single color light sources.